A water tight sliding door applied in ships requires a tight sealing contact between the door unit and the door frame, which surrounds the passage opening. The contact between the door unit and the frame must therefore be continuous all over the contact path. Sliding door arrangements of ships usually require high torsional and bending resistivity, as a result of which the frame and the door are usually rigid. Another alternative is known from the Finnish Patent publication 61946, in which the frame and the door unit are provided with flexible members, by which a continuous contact between the door unit and the frame is secured.
For a closure of the passage opening, the door unit is in both arrangements brought in contact by means of guiding wedge members, so that the door unit approaches the frame in a small approach angle. Hereby the door unit and the frame, or the sealing members thereof, are brought in a rubbing or sliding contact before the door unit motion stops. A similar rubbing contact appears during the initial opening phase of the passage, also. One drawback of the rubbing phenomenon is the wear of the sealing members. Furthermore, a portion of the driving power of the door unit motor is consumed only to overcome the rubbing friction.